WASHINGTON, March 26 (Reuters) - A Russian military contingent that arrived in Venezuela over the weekend, drawing U.S. condemnation, is believed by the U.S. government to be made up of special forces including "cybersecurity personnel," a U.S. official told Reuters on Tuesday.

The official, speaking on condition of anonymity, said the United States was still assessing the Russian deployment, which Washington has called a "reckless escalation" of the situation in Venezuela.

Two Russian air force planes landed outside Caracas on Saturday carrying nearly 100 Russian troops, according to local media reports, two months after the administration of U.S. President Donald Trump disavowed Venezuelan President Nicolas Maduro.

Venezuela's government has confirmed two planes landed from Russia at the weekend and were authorized by Maduro but has given no more details.

The Trump administration has recognized opposition leader Juan Guaido as the country's legitimate president and demands that Maduro step down. Russia has described this as a U.S.-backed coup against the socialist government.

The U.S. determination that the Russian contingent includes cybersecurity specialists suggests that part of their mission could be helping Maduro's loyalists with surveillance as well as protection of the government's cyber infrastructure.

Russia's main objective in providing the military assistance, including cyber experts, would likely be to help shield Maduro from "regime change" and ensure a foothold for Moscow in Latin America, according to a source familiar with U.S. government assessments of Venezuela. Russia also has major energy investments in OPEC member Venezuela.

Russia's foreign ministry said on Tuesday that the presence of "Russian specialists" in Venezuela was governed by a military-technical cooperation agreement between the two countries. It did not provide further details.

U.S. Secretary of State Mike Pompeo told his Russian counterpart Sergei Lavrov in a phone call on Monday that Washington would "not stand idly by" as Russia backed Maduro.

The United States and most Western countries have backed Guaido while Russia, China and Cuba are among those that have continued to support Maduro, who retains control of Venezuela's state institutions, including the military.

On Tuesday afternoon the Lima Group of Latin American countries said in a statement it was concerned about the arrival of military airplanes in Venezuela.

"We reiterate our condemnation of any military provocation or deployment that threatens peace and security in the region," said the group formed in 2017 to pressure Maduro, which includes Brazil, Canada, Colombia and Peru.

U.S. Senator Bob Menendez, ranking Democrat on the Senate Foreign Relations Committee, sent a letter to Pompeo on Tuesday urging him to determine if Venezuela, Cuba and Nicaragua should face mandatory U.S. sanctions for conducting significant transactions with the Russian defense and intelligence sectors. (Reporting by Matt Spetalnick, additional reporting by Mark Hosenball, Editing by Richard Chang and Rosalba O'Brien)

Our global editorial team of more than 50 journalists and about 250 freelancers covers the world’s under-reported stories at the heart of aid, development, women’s and LGBT+ rights, human trafficking, property rights, and climate change.